Manufacture of wrought iron



Patented Sept. 13, 1938 PATENT OFFICE 2,129,716 MANUFACTURE OF WROUGHT IRON Edward Edgeworth,

B. Story, Dormont, and Evard P. Best,

Pa., asslgnors to A. M. Byers Company, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing.

Application March 30, 1931,

Serial No. 133,808

1 4 Claims.

This invention relates to the manufacture of wrought iron, and more particularly to the manufacture of wrought iron by the now well known Aston process in which molten ferrous material is admixed with molten slag to form a wrought iron sponge ball.

It has long been recognized that the temperature relationship between the molten ferrous material and the molten slag must be controlled within certain fairly well defined limits in order that the best results may be obtained. However, the eifecting of the desired temperature control has presented certain difficulties which prior to the present invention have not been overcome with entire success.

'In the modern Aston process as carried out at the Ambridge plant of A. M. Byers Company molten ferrous material is admixed with a quantity of molten slag more than suilicient to form with the ferrous material a wrought iron sponge ballso that there is formed a sponge ball with an excess of molten slag. The excess slag is separated from the ball and is reused in the formation of subsequent balls, being replenished from time to time as necessary with additional molten slag. The balls now being made normally range in size from two to eight tons, and the cycle of operations is carried out much faster than heretofore. Certain improved methods of procedure and apparatus bringing about materially increased speed of operation are disclosed and claimed in our copending application Serial No.

filed of even date herewith.

The practice of replenishing with molten slag, the increased size of the balls formed and the increase in the speed 'of operation have rendered increa'ingly diflicult the problem of temperature control. All of the factors mentioned tend to undesirably increase the temperature of the slag, and on many occasions great difiiculty has been experienced in keeping the slag temperature sufliciently low to insure a proper disintegration of the molten ferrous material. It is well recognized that when the slag temperature becomes too great the molten ferrous material will not properly disintegrate and a ball of low or non-uniform quality will result.

In the early days of the Aston process when comparatively small sized balls were produced at comparatively slow speed without replenishment of the excess slag with molten slag it was proposed to introduce cold pulverized slag into the slag receptacle during the processing operation to keep down the temperature of the slag bath. However, this did not prove satisfactory,

(or. "are the cold pulverized slag interfering with proper disintegration of the metal. Other expedients for keeping down the slag temperature were resorted to, as, for example, the use of a plurality of slag receptacles in which the processing 5 operation is carried on more or less simultaneously, resulting in a considerable time lagduring the cycle, particularly while the excess slag is being decanted and the balls dumped. Such method obtains good temperature control but greatly impairs the efiiciency of the operation.

We have discovered that under present day conditions as above described proper slag temperature control can be eifected by introducing into the slag receptacle after completion of the processing operation a quantity of relatively cold solidified slag. In this way we are able to reduce the slag temperature without interfering with proper disintegration of the ferrous material during processing. In other words, the temperature control is effected in advance of the succeeding processing operation in which the temperature control is felt. The cold solidified slag which is introduced has an opportunity to melt and homogenize with the molten slag in advance of the processing operation so that simply by control of the quantity of solidified slag introduced substantially ideal conditions of operation may be produced with virtual certainty.

The cold solidified slag is introduced in substantiai quantities, the exact quantity depending upon the mass and temperature of the slag and the temperature reduction desired. Up to 200 or 300 pounds of cold solidified slag may be introduced at each cycle when balls of the sizes above mentioned are being formed. In the course of a days time the amount of cold solidified slag thus introduced mounts up greatly and may, for example, total in the neighborhood of 25 to 30 tons per day or even more. The economy of the process is thus further increased, as no external heat need be applied to melt this substantial quantity of slag. Thus despite conditions which are unfavorable for temperature control we are able at the same time to control the slag temperature and increase the efiiciency of the plant.

The process is preferably carried out by providing a receptacle of molten slag at proper temperature and pouring into the slag bath molten ferrous material of characteristics suitable for the manufacture of wrought iron as well known. The ferrous material disintegrates in the slag bath and builds up onthe bottom of the receptacle the well known wrought iron sponge ball. An excess of slag is used so that after formation of u the ball there remains in the receptacle with the ball a quantity of excess molten slag whose temperature has been raised by the molten ferro material.

We find it preferable to introduce the cold solidified slag after completion of the pouring or processing-step and before separating the ball and excess slag. It is convenient to introduce the cold solidified slag into the receptacle while it is still at the processing station immediately after completion of the pour. Thus the cold solidified slag is introduced into the bath of molten slag when the bath is at substantially its highest temperature but after formation of the sponge ball has been completed so that there will be no possibility of any of the relatively cold slag getting into the sponge ball before such slag is competely melted and has had an opportunity to homogenize with the remainder of the molten slag. Thereafter the excess slag, including the slag introduced after processing, is separated from the ball, the preferred method of effecting such separation being by decanting off the slag. The decanting assists in mixing and homogenizing the slag and thus aids in rapidly melting the cold solidified slag. If the receptacle containing the decanted slag is returned directly to the processing station the slag will have sufficiently homogenized by the time the succeeding processing operation is commenced to enable obtaining of the desired results. i

The cold solidified slag may, if desired, be incorporated with the excess slag during the decanting step, as by being introduced into the stream of slag being decanted or into the receptacle into which the decanting is taking place.

It is thus afforded an excellent opportunity of melting and homogenizing with the decanted slag. The cold solidified slag may be incorporated with the excess slag after separation of the ball and excess slag. However, when this is done it is desirable that the slag (i e., the excess slag and the added slag) be admixed, as, for example, by decanting into another receptacle in order to afford the added cold solidified slag a suflicient opportunity to melt and homogenize with the molten slag before the succeeding processing operation. Alternatively, when the cold solidified slag is added after separation of the ball and excess slag the slag may be replenished with additional molten slag which upon entry into the receptacle has the effect of agitating the slag bath and thus melting and homogenizing the slag added in cold solidified form.

Ordinarily replenishment with additional molten slag is not effected during each cycle of operation. It may be effected, for example, every third or fourth cycle. When replenishment is effected the additional molten slag may be introduced either before, during or after separation of the ball and excess slag. Generally it is found most convenient to replenish after separation, that is, in the present day operation of the Ambridge plant, after the excess slag has been decanted from the receptacle containing the ball into another receptacle. Thus, as above mentioned, if the cold solidified slag is added after decanting but before replenishment with molten slag the introduction of the replenishing slag as:- sists in melting and homogenizing the slag added as cold solidified slag. The amount of cold solidified slag which is added to obtain the desired temperature control is much less than the amount needed for replenishment to maintain the necessary slag volume and it does not take the place of replenishment with molten slag. Rather. the two go hand-in-hand in effecting the desired control of both slag volume and slag temperature.

As indicated above, the slag added as cold lolidified slag normally should be admixed with the molten slag before the succeeding processing operation. This is particularly true in igh speed operation. If the time lag is sufilciently great the solidified slag may sufilciently melt and homogenize with the molten slag without any admixture other than that caused by introduction of the solidified slag into the bath of molten slag, but it is preferable to aid in bringing this about by agitating the slag bath, as, for example, by introducion molten slag for replenishment after introduction of the cold solidified slag or by decanting the slag bath from one receptacle into another. This explains why it is preferableto introduce the cold solidified slag into the slag receptacle before separating the excess slag from the ball formed in the preceding processing operation. We have obtained excellent results in actual commercial operation by this method of temperature control.

While we have described certain present preferred methods of carrying out our invention, it is to be distinctly understood that the same is not limited thereto but may be otherwise variously practiced within the scope of the following claims.

We claim:

1. In the manufacture of wrought iron by the Aston process, the steps comprising admixing molten ferrous material with a quantity of molten slag more than sufficient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, separating the ball and excess slag, simultaneously with the separation of the ball and excess slag incorporating with the excess slag a quantity of relatively cold solidified slag, and utilizing the mass of slag thus produced as at least a part of a quantity of molten slag for admixture with ferrous material to form another wrought iron sponge ball and admixing molten ferrous material with said second mentioned quantity of molten slag to form said second mentioned wrought iron sponge ball.

2. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufficient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, decanting the excess slag from said receptacle into another receptacle while retaining the ball in the first mentioned receptacle, simultaneously with such decanting incorporating with the excess slag a quantity of relatively cold solidified slag, and utilizing the mass of slag thus produced in the second mentioned receptacle as at least a part of a quantity of molten slag for admixture with ferrous material to form another wrought iron sponge ball, and admixing molten ferrous material with said second mentioned quantity of molten slag to form said second mentioned wrought iron sponge ball.

3. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufficient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge mentioned receptacle, simultaneously with such decanting incorporating with the excess slag a quantity of relatively cold solidified slag by introducing such relatively cold solidified slag into the stream of slag being decanted, and utilizing the mass of slag thus produced in the second mentioned receptacle as at least a part of a quantity of molten slag for admixture with ferrous material to form another wrought iron sponge ball and admixing molten ferrous material with said second mentioned quantity of molten slag to form said second mentioned wrought iron sponge ball.

' 4. In the manufacture of wrought iron by the Aston process, the steps comprising admixing in a receptacle molten ferrous material with a quantity of molten slag more than sufllcient to form with the ferrous material a wrought iron sponge ball and thereby forming a wrought iron sponge ball with an excess of molten slag, decanting the excess slag from said receptacle into another receptacle while retaining the ball in the first mentioned receptacle, simultaneously with such decanting incorporating with the excess slag a quantity of relatively cold solidified slag in the second mentioned receptacle, and utilizing the mass of slag thus produced in the second mentioned receptacle as at least a part of a quantity of molten slag for admixture with ferrous material to form another wrought iron sponge ball and admixing molten ferrous material with said second mentioned quantity of molten slag to form said second mentioned wrought iron sponge ball.

EDWARD B. STORY. EVARD P. BEST. 

